HIGH-RESOLUTION ELECTRON-MICROSCOPY OF AL-NI-FE DECAGONAL QUASI-CRYSTAL

The structure of a stable decagonal quasicrystal with 0.4 nm periodici ty, formed in a conventionally solidified alloy with composition Al71. 6Ni23.7Fe4.7, was investigated by high-resolution electron microscopy. It was found that this decagonal phase is one of the best-ordered qua sicrystals, without any detectable linear phason strain and with only weak random phason strain. The structure is interpreted as an aperiodi c tiling of decagonal atom columns with a diameter of about 1.2 nm. Th e atomic arrangements in special local regions are discussed on the ba sis of computer simulations.